Verapamil does not alter succinylcholine-induced increases in serum potassium during halothane anesthesia in normal dogs.

Six dogs were studied to determine whether verapamil pretreatment exacerbates the increase in serum potassium levels associated with succinylcholine. Dogs were anesthetized with halothane, 1.26 +/- 0% (mean +/- SEM; end tidal). Arterial blood-gas tensions, blood pressure, heart rate, temperature, and serum potassium levels were measured. Each dog underwent control and experimental studies separated by seven days. In the experimental study, a 0.15 mg/kg bolus of verapamil was followed by a 4.0 micrograms X kg-1 X min-1 continuous infusion of verapamil. Normal saline was used in the control study. Succinylcholine, 1 mg/kg bolus, was given 10 min after the initial saline or verapamil bolus. Vital signs again were measured 1, 3, 5, 10, and 15 min after succinylcholine, and plasma verapamil levels were measured 8 and 15 min after verapamil administration. Serum potassium concentrations increased from 3.9 +/- 0.2 to 5.0 +/- 0.2 mEq/L in control studies and from 3.7 +/- 0.2 to 4.8 +/- 0.3 mEq/L in animals pretreated with verapamil. Verapamil pretreatment does not alter the increase in serum potassium induced by succinylcholine in normal dogs.